How to empty a socket in python?

Question

I need to empty the data on a socket (making sure that there is nothing to receive). Unfortunately, there is no function for this in the python socket module.

I've implemented something this way:

def empty_socket(sock):
    """remove the data present on the socket"""
    input = [sock]
    while 1:
        inputready, o, e = select.select(input,[],[], 0.0)
        if len(inputready)==0: break
        for s in inputready: s.recv(1)

What do you think? Is there a better way to do that?

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Update: I don't want to change the socket timeout. What's why i prefer a select to a read.

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Update: The original question was using the 'flush' term. It seems that 'empty' is a better term.

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Update - 2010-02-27 : I've noticed a bug when the pair has closed. The inputready is always filled with the sockets. I fixed that by adding a maximum number of loops. Is there a better fix?

Answer 1

If by "flush" you mean throw away any pending incoming data then you can either use select() like you do, or set the socket to nonblocking and read in a loop until you're out of data.

Also note that (from the Linux manpage):

Under Linux, select() may report a socket file descriptor as "ready for reading", while nevertheless a subsequent read blocks. This could for example happen when data has arrived but upon examination has wrong checksum and is discarded. There may be other circumstances in which a file descriptor is spuriously reported as ready. Thus it may be safer to use O_NONBLOCK on sockets that should not block.

Spurious readiness notification for Select System call

And as has been noted by others, "flush" usually refers to output.